Maja Krzic

Prospective Graduate Students / Postdocs

This faculty member is currently not actively recruiting graduate students or Postdoctoral Fellows, but might consider co-supervision together with another faculty member.

Associate Professor

Research Classification

Research Interests

Soil quality
Soil management

Relevant Degree Programs

Affiliations to Research Centres, Institutes & Clusters


Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - May 2021)
Soil properties and land use affecting soil water dynamics in Andisols and Inceptisols at two mid-elevation sites in the Colombian Andes (2018)

Soil has a crucial role in the terrestrial component of the hydrologic cycle, regulating the availability of water for ecosystem services. Yet relationships between soil properties and land use for the major soil types in the Colombian Andes have not been extensively studied. This study evaluated soil water (SW) dynamics of two soils types, belonging to the most common soil orders in the Colombian Andes, Andisols and Inceptisols. The research was conducted in two watersheds at mid-elevation, and focused on the relationships between mineralogical, physical and chemical soil properties with soil water dynamics, including soil water retention (SWR) and field saturated hydraulic conductivity (Kfs). The Andisols and Inceptisols of this study have a large total porosity compared to typical clay soils, but Andisols, showed higher SWR at every soil tension relative to Inceptisols. Notwithstanding the high hygroscopic water (θPWP), both soils have a wide pore size distribution, with similar gravitational water and plant available water storage capacities. Despite differences in climate and soil parent material between watersheds, the presence of colloids with high specific surface area in both soils (allophane, imogolite, ferrihydrite and organo-metallic complexes in Andisols and ferrihydrite and Al/Fe oxides in Inceptisols) contribute to high SWR. Within each site, differences in SWR between land uses appear minimal, although soil organic carbon was lower under pasture in both soils. The limited differences in SWR between natural forest and pasture appear to reflect the effects of short-range order (SRO) minerals and organo-metallic compounds on SWR, which offset differences in SOC between natural forest and pasture.Quasi steady-state infiltration rates measured in the field did not correspond to expected values based on texture alone, highlighting the importance of field based measurements, particularly in soils with SRO minerals. Additionally, there was a pronounced seasonal difference in Kfs under pasture in both soil types, and a negative correlation of soil water content with Kfs in Inceptisols. Determination of physical, chemical and mineralogical properties was found to be crucial in understanding soil water dynamics in this study, and future work should include an assessment of SRO minerals in addition to SWR characteristics.

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Relative bulk density as an index of soil compaction and forest productivity in British Columbia (2009)

Soil compaction often limits conifer regeneration on sites degraded by construction of landings and roads, but inadequate understanding of compaction characteristics has sometimes led to inappropriate rehabilitation efforts. This warrants development of new methods to assess compaction and its relation to tree growth. The objective of this study was to develop a high-level integration indicator that will characterize compaction of forest soils and that could be correlated to tree height growth. Mineral particle density of soils from interior British Columbia (BC) forests varied significantly among the geographic locations. Oxalate-extractable Fe- and Al-oxides and particle size distribution (PSD) were related to soil and mineral particle densities, while soil organic matter (SOM) and Al- and Fe-oxides were important soil properties in relation to soil particle density. The significance of levels of single soil properties in predicting maximum bulk density (MBD) were in the order: plastic and liquid limits, organic matter content, oxalate-extractable oxide, and PSD. Stratification of the sample according to Atterberg limits improved the predictability of MBD, and variation in particle density was included in the prediction by other soil properties used in the models. Height growth of interior Douglas-fir (Pseudotsuga menziesii var. glauca [Bessin] Franco) was restricted when relative bulk density (RBD) was > 0.72. For lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) and hybrid white spruce (Picea glauca [Moench] Voss × engelmannii Parry ex Engelm.), an RBD of 0.60 - 0.63 corresponded to maximum height growth, while that of 0.78 - 0.84 appeared to limit height growth. The presence of surface organic material mitigated compaction and was often associated with lower RBD. Interior Douglas-fir and lodgepole pine planted in low elevation sites in north-central BC did not grow well and their height growth was weakly related to RBD. The results suggest that soil rehabilitation should be considered on disturbed sites where soil RBD is > 0.80.Findings in this study have implications in assessing forest soil compaction and its effect on site productivity. The results will help predict soil behaviour and associated tree growth in response to timber harvesting and site rehabilitation.

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Master's Student Supervision (2010 - 2020)
The effects of nitrogen fertilizer rates and planting date on greenhouse gas emissions and potato production in Delta, British Columbia (2020)

Crop production is a known source of CO₂, N₂O, and CH₄ emissions, yet greenhouse gas (GHG) emissions data from crops in the Lower Fraser River Valley (LFRV) are limited. Potatoes are the most prominent cash crop in the LFRV and are often associated with excess nitrogen (N) fertilizer use, a primary source of N₂O emissions. Soils in this region have poor drainage, which is exacerbated by precipitation in the spring and fall. Consequentially, the variable soil workability impacts the timing of potato planting and harvest. The objective of this study was to assess how N fertilizer rates (0, 90, and 120 kg N ha⁻¹) and planting date (typical and late) influence GHG emissions, potato production, and soil properties. The field experiment was established in 2018 at two fields in Delta, British Columbia (BC); one was classified as productive and the other as unproductive. Yield increased with N fertilizer rate at the productive field, but a cost-benefit analysis showed that the increase in yield between the 90 and 120 kg N ha⁻¹ treatments did not significantly outweigh the additional fertilizer costs. The yield at the unproductive field did not respond to N fertilizer, likely due to pre-existing salinity and drainage issues. Planting date did not affect yield at either of the fields. Over the growing season (May to October), there were no differences in total GHG emissions with either N fertilizer rate or planting date. November sampling at the productive field, following a precipitation event, showed N₂O emissions increase with N fertilizer treatments. To supplement the field experiment, a soil incubation experiment was conducted to better understand the interactive effects of temperature (4ºC and 20ºC) and soil water content (20% and 40% volumetric water content) on GHG emissions and soil N dynamics in soils fertilized with inorganic N. Nitrous oxide emissions were near zero when temperature was 4ºC or volumetric water content was 20%. This study emphasizes the importance of reviewing N fertilizer management at fields with signs of soil degradation that will, most likely, respond differently to N fertilizers than productive fields.

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The effects of 2- and 3-year grassland set-asides on plant available nitrogen and greenhouse gas emissions in Delta, British Columbia (2019)

Since 1993, the Grassland Set-Aside (GLSA) Stewardship Program has incentivized farmers in the western Fraser River delta, British Columbia, Canada to plant a grass-legume mixture on active cropland and leave it fallow for 1-4 years to improve soil quality and provide wildlife habitat. Benefits to wildlife are well documented, but not well understood for soil quality. Study objectives were to quantify the effects of 2- and 3-year GLSAs on plant available nitrogen (N), crop production, soil quality, and greenhouse gas emissions. A field experiment was established in 2017 on a productive and unproductive field with fertilizer treatments (0 and 80-kg N ha⁻¹) compared across GLSA treatments (i) AC – GLSA biomass removed and (ii) 2G – 2-year-old GLSA biomass was incorporated, and seeded with beans. In 2018, fertilizer treatments (0 and 100-kg N ha⁻¹) were compared across the same GLSA treatments and (iii) 3G –3-year-old GLSA biomass was incorporated, and seeded with potatoes. Active carbon (POXC) and aggregate stability (MWD) were measured 3 times per growing season, plant available nitrogen (PAN) was sampled every 2 weeks from May-September, and carbon dioxide, methane, and nitrous oxide were measured weekly from May-September and every 3 weeks from October-April. MWD increased in 2G and 3G in the year of incorporation relative to AC and POXC increased for 3G relative to AC and 2G. Average seasonal PAN did not differ across treatments but was higher earlier in the season for 2G. Bean yields were greater in 2G compared to AC in the productive field, but otherwise crop yields did not respond to GLSA. N content of bean crops did not differ between treatments, was higher for 3G compared to AC in the unproductive field. 2G increased carbon dioxide emissions in 2018, but 3G only increased emissions in the 2018 production season. Nitrous oxide emissions treatments were higher in 2G treatments across all seasons, but lower in 3G treatments in the 2018 production season. Results suggest 2- and 3-year GLSAs do not increase average PAN to subsequent crops, but increase PAN earlier in the season, and increase crop yield and quality depending on subsequent crops.

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The effects of short-term grassland set-asides on soil properties in the Fraser River delta of British Columbia (2018)

The Grassland Set-Aside Stewardship Program provides cost-share payments to agriculture producers in the Fraser River delta (FRD) region of British Columbia for placing active cropland under a grass and legume vegetation mix for a one to four-year period. While long-term grassland set-asides (GLSA) have been found to improve soil structure, reduce compaction, and increase soil organic matter; short-term set-asides (
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The long-term effects of biosolids on rangeland soil quality and plant community in the central Interior of British Columbia (2018)

Biosolids have been shown to improve forage production and soil quality on semi-arid rangelands in the short-term. The objective of this study was to assess the long-term effects of a single, surface biosolids application on rangeland soil quality, forage production and plant community composition. In 2002, the experiment was established on a ranch in the central Interior of British Columbia, where two treatments were evaluated: surface biosolids application at 20 Mg ha-¹ and a control (no biosolids). Both treatments were replicated in four blocks, which were then excluded from grazing for 14 years. In 2016, soil samples were collected in April, June, August and October to assess various soil quality indicators, while forage quality indicators were assessed in June 2016. Fourteen years following the biosolids application, aboveground plant biomass was almost two times greater with biosolids application than on control. Exposed mineral soil was significantly decreased in biosolids plots. Despite differences in aboveground biomass there was no difference in total soil C, permanganate-oxidizable C, or aggregate-protected total C and polysaccharides contents between biosolids and control plots. However, biosolids amended soil did exhibit significantly greater aggregate stability, lower pH, increased spring soil water content, and increased availability of soil P, Fe, Zn and Cu. Forage grown on biosolids plots had lower protein concentrations than control plots, but greater total protein due to the greater biomass. The biosolids application resulted in higher cover of native bluebunch wheatgrass in the long-term, along with >25% cover of agronomic perennial, Kentucky bluegrass. These results offer a demonstration of the potential long-term improvement in forage production that can occur under biosolids application without grazing, which was accompanied by somewhat mixed effects on soil quality and plant species composition.

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Ammonia emissions and dry deposition from broiler barns in the Fraser Valley of British Columbia (2016)

Ammonia emissions from commercial broiler operations have been noted as one of the potential contributors to the nitrate contamination of the Abbotsford-Sumas aquifer in southwestern British Columbia (BC). The localized dry deposition of this emitted ammonia was of special interest and had not been measured in any comparable climate. Three barns, on two farms, located on the aquifer were assessed from July 2011 to June 2012. Ventilation, emission, and deposition samples were taken weekly throughout the seasons to accurately characterize the impact on the local environment. Ventilation was measured using a Fan Assessment Numeration System and timers that recorded individual fan activity. Acid impinger traps were used to measure the ammonia emitted by the sidewall fans. A methodology for measuring dry deposition by exposing air-dried soil was modified to use small Petri dishes and a 24-hr exposure time. The modified dry deposition method was found to be robust and effective for the requirements of this study. Dishes of soil were placed 2.1 and 3.6 m in front of and between each fan, as well as around the barns and farm properties. Ventilation rates for the barns were significantly and positively correlated with bird age and exterior temperature. Ammonia emissions were correlated with bird age and the emission factors for the three barns ranged from 0.19-0.37 g NH₃ bird-¹ day-¹ with annual ammonia emissions for each barn reaching 600 to 815 kg NH₃. Dry deposition levels on the two farms exceeded 50 kg NH₃ annually although this accounted for less than 10% of the ammonia emitted. The deposition levels were highest near the barns and were concentrated directly under the sidewall fan hoods. These levels of ammonia show significant potential to cause nitrate to leach into the groundwater and further contaminate the aquifer but future work and upscaling of data collection are needed.

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Blending Multimedia and Campus-Based Learning to Enhance Learning about Forest Floor and Humus Forms (2015)

Given the functions of forest organic soil horizons in carbon sequestration, biodiversity and nutrient cycling, coupled with the fact that the forest floor is often not described in soil surveys, it is important that forestry professionals learn to classify organic horizons and humus forms. The current generation of undergraduate students appreciate having access to multimedia and online resources in their learning, and prefer active, collaborative experiences of the concepts they are learning in the classroom. With technological advances, modernizing curriculum by blending campus-based learning and multimedia is ever easier to accomplish. The objectives of this study were to: (1) develop blended-learning activities, combining campus based learning and multimedia web-based resources, to teach forest floor description and classification; and (2) conduct exploratory factor analysis of student survey responses to assess student opinions about the application of the blended-learning method. The Forest Floor web-based educational resource and campus-based activities were developed with the contributions of a team of experts in soil science, web and multimedia design, and science education. Ninety-four percent of students agreed or strongly agreed that the Forest Floor web-based resource was helpful for learning forest floor concepts, 79% that describing samples in class was essential for understanding the properties of organic horizons, and 81% that they were able to relate information in the Forest Floor web-based resource to their own samples used in an in-class activity indicating that students appreciated the blended learning methodology. Based on the survey responses five implicit factors were interpreted: (1) satisfaction with the web-based educational resources as learning enhancements; (2) success of presentation of concepts using a blended learning method; (3) student self-assessment of learning; (4) student learning preferences in accessing materials; and (5) website usability. Student feedback suggests that the blended learning activities were appreciated and met the learning objectives. This study also provides an example for conducting exploratory factor analysis of blended learning interventions and provides factors that may be verified through confirmatory factor analysis.

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Effects of grassland set-asides on selected soil properties in the Fraser River Delta of British Columbia (2014)

Grassland set-asides (GLSAs) have been used to encourage environmental stewardship on agricultural land in the Fraser River delta of British Columbia (BC) since 1994. Through this Grassland Set-aside Stewardship Program, farmers plant a mixture of grasses and legumes in place of harvestable crops for a minimum of one full year and the farmers then receive payment for establishing these short-term grasslands. Grassland set-asides are typically established on degraded fields. Although improving long-term soil quality is a key objective in the GLSA Program, evaluations of GLSA management effects on the soil have been few and limited in scope. The objectives of this study were to determine the effects of GLSA management and GLSA age on selected soil properties in agricultural fields in the Fraser River delta. Three GLSA field sites – ranging in age from two, three, and six years – were compared to three adjacent cropped potato fields for the following soil properties: total soil C and N, mechanical resistance, bulk density, aeration porosity, and aggregate stability. Relative to the Cropped treatment, the GLSA treatment did not result in an increase in total soil C or N, but did result in lower soil mechanical resistance in the upper 30 cm depth, and higher aeration porosity, and aggregate stability. The differences observed between the Cropped and GLSA treatments were most pronounced on the site with the six-year-old GLSA, indicating reduced compaction and improved soil structure as a GLSA ages. Baseline measurements of the soil prior to GLSA establishment are recommended to track changes to the soil over time and to improve the efficacy of GLSA management as a remediation strategy by pinpointing underlying soil issues that could be addressed through other corrective management (i.e. sub-soiling, liming, etc.). Soil mechanical resistance, aeration porosity, aggregate stability, pH, salinity, and mineralizable N are suggested as valuable, responsive indicators of GLSA management effects on the soil.

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A Comparison of the Effects of 20 and 30 Years of Grazing on Grassland Soil Properties in Southern British Columbia (2011)

Although numerous studies have been conducted on rangeland soil quality in Alberta, Manitoba, Saskatchewan, as well as in the Great Plains, there has been little documentation of the response of soil properties to time of grazing and stocking rate treatments for the grasslands of the southern interior of BC. In the Lac Du Bois range in Kamloops, BC, the current moderate stocking rate of 2 AUM ha⁻¹ was based on a desired available forage use of 50%. Livestock is moved up and down an elevation and productivity gradient over the grazing season so that pastures located midway up the gradient are grazed either in the spring or fall. The objectives of this study were to determine (1) the effects of spring and fall grazing treatments on selected soil properties after periods of 20 and 30 years and (2) the effects of 0 and 2 AUM ha⁻¹ grazing rates on selected soil properties after periods of 20 and 30 years. The spring grazing treatment led to greater soil bulk density, mechanical resistance, pH, as well as lower polysaccharides and CEC relative to the fall grazing treatment. The grazing rate of 2 AUM ha⁻¹ led to greater soil mechanical resistance and pH, as well as lower soil polysaccharides and LOMF relative to the ungrazed control. After 30 years of grazing, soil bulk density was greater in the 0-7.5-cm depth under the 2 AUM ha⁻¹ treatment relative to the ungrazed exclosure in spring-grazed but not in fall-grazed areas, indicating that this stocking rate, when used for spring grazing, has led to soil compaction. Rangeland managers in the southern interior of BC should consider adjustments of time of grazing and stocking rate recommendations when these have been solely on vegetation responses, and should consider including soil properties in rangeland health assessments.

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An assessment of soil water repellency after wildfire in southern British Columbia : comparison of methodologies and predictive indicators (2011)

Current studies of soil water repellency show that there are multiple contributing factors to its presence and persistence. Water repellency in soils of the Southern Interior of British Columbia has economic implications, as it can contribute to large scale landslides, and management implications as it affects hydrology and wildfire rehabilitation.The purposes of these studies were twofold. The first assessed three appropriate methods for testing soil water repellency of burned and unburned soils from eight areas in southern British Columbia. These tests were performed in laboratory conditions as well as in situ. The Concentration of Ethanol Drop (CED), Mini-Disk Infiltrometer (MDI) and Spatial Repellency Index (SRI) tests were all used, and the results compared to assess whether all were valid. The studies indicated that the MDI, CED and SRI tests are reliable to detect at least the presence or absence of water repellency in both field and laboratory conditions. The second study assessed whether wildfire would increase the presence and degree of water repellency in the soils one or two years after fire, and whether total organic content, texture and ambient moisture content could be used to predict this soil trait. Wildfire did not increase the presence or degree of water repellency, and soil texture, organic matter content and moisture content were not found to be reliable indicators of soil water repellency in these soils. This study showed that water repellency exists in burned and unburned forest soils in BC, and that various methods can be used to test for it. Further detailed studies are needed on the predictors on forest soils in British Columbia.

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Development of an innovative web-based teaching tool illustrating land use impacts to soil quality and formation (2010)

No abstract available.


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